An existing power tool may be powered by a battery pack and a motor is driven by a drive circuit to operate. However, in the current power tool, especially a hand-held power tool based on a 1P battery pack, the impulse current of the battery pack and an output torque of the motor are difficult to control under heavy loads. Here, the 1P battery pack refers to a battery pack composed of a plurality of single battery cells connected in series.
The existing power tool, especially a circular saw or an electric drill, will have a maximum impulse current up to 100 A or above in the locked rotor state. A High impulse current will seriously damage the power supply device of the power tool, such as the battery pack, thereby affecting the safety of the power tool.
Therefore, for safety reasons, the existing power tool is provided with an overload protection device, but the device would directly turn off the motor when the heavy loads of the power tool reach a preset threshold to prevent a current of the motor from impacting the power supply device. In this overload protection mode, the motor generally needs to be turned off when the maximum output torque of the hand-held power tool reaches 3.5N·m. That is, the practical load the power too can bear is only 3.5N·m. Under heavy loads, the anti-blocking capability and user experience of the existing power tool are difficult to meet the requirements.
Therefore, there is an urgent need to increase the maximum output torque of the power tool.